Topic: Center stand frame repair question

[arncruz]

I have an early sandcast frame that is missing the center stand brackets. I wanted to get some advice on repair project. I have a donor Cb750 ko and k1 frame that I can cut the whole middle frame section or just the brackets out. My question is would it be better to weld the brackets individually to the sc frame or should I cut the whole middle frame section with the brackets in place and weld it to the sandcast frame?

[BenelliSEI]

I assume the centre stand brackets were removed without too much damage to the cross member? If so, I’d leave it there. By just reattaching the brackets, you avoid the risk of any distortion to the side frame rails when welding in a cross tube.

[BPellerine]

I just removed the brackets from another frame,positioned them with steel rivets,and put the centre stand tube through them tightened it up a bit to keep them inline and tacked before welding.bill

[754]

 I am thinking the only truly easy way is to cut the cross tube out, with the center stand mounts and bar for spring intact.
 Then cut the bar on the early frame out a tad shorter. Then trim to fit, orient innthe right place, and just weld around the tube twice.
 at first though inspect the keeper farm for rot by the side stand mount and motor mount area.

[Don R]

 If you do cut out the frame tube (I wouldn't) bolt an engine case into the frame to be sure alignment stays the same.

[calj737]

Then trim to fit, orient innthe right place, and just weld around the tube twice.

Once is more than enough.

When you weld a tube into place, you'll either need a vent hole in one end of the parent frame, the tube, or you'll have a heck of a time closing your weld up. The accumulated gas and pressure internally to the tube will blow out the final weld closing. So leave a small gap in the weld, let it cool fully, then you can zip it closed. Or vent it.

[754]

2  welds if you cut tube out.
 3 or 3 if you replace  the 2 brackets and the round bar.

The only way you will get nice donor bits is to cut the tube out of a frame,  then removing them get easier m a lathe may help.

[Don R]

Then trim to fit, orient innthe right place, and just weld around the tube twice.

Once is more than enough.

When you weld a tube into place, you'll either need a vent hole in one end of the parent frame, the tube, or you'll have a heck of a time closing your weld up. The accumulated gas and pressure internally to the tube will blow out the final weld closing. So leave a small gap in the weld, let it cool fully, then you can zip it closed. Or vent it.

Yup I've had that happen on that tube. Race car builders drill an 1/8" hole where it will drain to let the pressurized air out.

[bamacb]

I've replaced brackets / tubes using donor frame parts many times . Sometimes it's the only way to save a certain needed frame. If you have average welding skills and use logic then it's no problem. I prefer to remove needed brackets and keep as much of the original frame intact as possible.

[754]

 Welding them back on , is not a huge problem.
Welding them on so that you cannot tell  and retain the value of an early  frame.. that is harder to acheive.

[bamacb]

Welding them back on , is not a huge problem.
Welding them on so that you cannot tell  and retain the value of an early  frame.. that is harder to acheive.

Lucky I've not had that problem. At this point with the originals cut off I fail to see how anything short of a botched job would lower the value farther

[BPellerine]

alot of the welds on early frames were not all that pretty,that I saw anyway.bill

[754]

I know that so if you make them too nice it's wrong  if you tig them it's wrong.
Meanwhile if you can get a good weld around a tube in 2 spots, and hide that, the welds on the mounts will be perfect..

[BPellerine]

for me I did not want to cut anything that was not cut already,I had alot of repairs to do,I guess resto would be a diff thing.bill

[arncruz]

Thanks guys for the suggestions!  As always you guys are a wealth of information and experience.  I'm leaning towards just cutting the tube out with the brackets in place and welding it into place.  Has anyone done this and can you post pictures of the repair?
Thanks in advance
Arnold

[calj737]

I'm leaning towards just cutting the tube out with the brackets in place and welding it into place.

To Frank's point: if you want "originality" you will have to MIG weld it. I'd use 0.023 -S6. If you want it clean and tidy, TIG weld it. Either way, some diligent work afterwards with some files to dress the welds off would help conceal the recent repair.